While Paul mentions routinely having issues getting accurate focus with the NEX, Mel mentions having only occasional difficulty. RonFrank adds that it's more problems in low light and trickier focus challenges where he sees the NEX having focus problems, and many mention using DMF or manual focusing as an aid or backup. So to add to the myriad of different experiences, consider that I have no focus problems with two different NEX models, both CDAF only and not even with the PDAF on sensor...I accurately get focus on every item I intend, I shoot moving targets and in low light very frequently, and I also shoot with a DSLR that has a traditional phase-detect AF system and fantastically accurate focus, and do not find the NEX to be appreciably less accurate in almost any situation, and only a little slower to acquire something like a moving subject, and not as able to continuously track and adjust focus as the subject moves compared to a DSLR.

I'm sure much has to do with each person's experience, settings, style, etc. But just know that while some mention struggling mightily with NEX AF, others only have periodic issues, others still think it only lacks in certain conditions, and still a few more like myself find the AF system to be perfectly accurate and reliable in nearly any condition.